Mold carriers for use in rotational casting



Sept. 19, 1961 G. T. PARSCH MOLD CARRIERS FOR USE IN ROTATIONAL CASTING Filed Feb. 26, 1958 3 Sheets-Sheet 1 FIG. 2

INVENTOR. GILBERT THOMAS PARSCH QZH 32 1 ATTORNEYS I Sept. 19, 1961 G. T. PARSCH MOLD CARRIERS FOR USE IN ROTATIONAL CASTING Filed Feb. 26, 1958 3 Sheets-Sheet 2 INVENTOR. GILBERT THOMAS PARSCH mm Om mm mm MQE ATTORNEYS G. T. PARSCH MOLD CARRIERS FOR USE IN ROTATIONAL CASTING Filed Feb. 26, 1958 11 6 9 1 9 1 t P e S 5 Sheets-Sheet 3 Ila FIG. 4

v w y 1 v in: v

F I G. 6

GILBERT THOMAS PARSCH BY 866 I x INVENTOR.

FIG. 5

ATTOR N EYS United States Patent MOLD CARRIERS FOR USE IN ROTATIONAL CASTING Gilbert Thomas Parsch, Akron, Ohio, assignor to The McNeil Machine & Engineering Company, Akron, Ohio, a corporation of Ohio Filed Feb. 26, 1958, Ser. No. 717,668

14 Claims. (Cl. 18-43) The present invention relates to improvements in rotat onal casting apparatus. More particularly, the invention relates to an improved mold carrier or spider for use with rotational casting apparatus.

In a process of rotational casting to which the invention is especially adapted, there is provided a series of hollow sectional molds which are loaded with a charge of plastisol such as a vinyl-resin compounded with a plasticizer. Plastisols of this type are well known in the art and are available from a number of sources. When the molds are charged, the spider is closed and locked and immediately thereafter is rotated simultaneously upon difierent axes to distribute the plastisol evenly over the inner surface of each mold. After the material has been gelled and fused by the controlled application of heat, the rotation of the spider is stopped and the spider is cooled to a degree where the molds can be opened and the finished article removed, whereupon the molds are readied for repeating the cycle.

The apparatus of the invention is particularly intended for use with a casting machine having one or more radially extending arms. Each casting arm may include a pair of shafts, one within the other, which are driven at differential Speeds to impart simultaneous rotation on divergent axes to the spider or mold carrier supported on the outer ends of the shafts. The rate of rotation of either shaft may be changed without changing the speed of the other shaft and thus the spider may be subjected to a variety of speed ratios with a resultant extreme application of centrifugal forces. A satisfactory spider or mold carrier should thus be light in weight yet constructed to resist deformation by the driving force of the casting machine. A satisfactory spider should be easily closed when cool yet easily opened when warm after emergence from a curing oven. Finally, a satisfactory spider must maintain the sectional molds closed and in proper alignment despite extreme application of centrifugal casting forces.

Accordingly, it is an object of the present invention to provide an improved mold carrier or spider for use with rotational casting apparatus.

It is a further object of the invention to provide an improved mold carrier or spider which is light in weight, which will resist deformation by the driving force of the casting machine, which will be easily opened and closed, which will resist the heat of a curing oven, and which will maintain the sectional molds closed and in correct alignment despite extreme applications of centrifugal casting forces.

These and other objects of the invention will be apparent in view of the following description of the invention taken in connection with the attached drawings.

In the drawings:

FIG. 1 is a plan view of a mold carrier or spider according to the invention adapted for carrying round or spherical molds;

FIG. 2 is a sectional plan view of a spider adapted for carrying oval molds;

FIG. 3 is an enlarged section taken substantially as indicated on line 3-3 of FIG. 1;

FIG. 4 is an end view taken substantially as indicated on line 44 of FIG. 3;

FIG. 5 is an enlarged section through an oval mold "ice taken substantially as indicated on line 5-5 of FIG. 2; and

FIG. 6 is an enlarged view of a mold half registering means for use with spherical sectional molds having continuous pattern molding surfaces.

A mold carrier or spider according to the invention includes a lower grid member adapted for attachment to a casting machine, an upper grid member yieldably hinged to the lower grid member, and coupling means extending axially between the grid members for locking the grids together in substantially parallel planes. A plurality of upper mold halves are resiliently mounted on the upper grid and a plurality of lower mold halves, aligned and mating with the upper mold halves, are movably mounted on the lower grid.

In the drawings, a mold carrier or spider according to the invention is indicated at 10. In FIG. 1, the spider 10 is adapted for carrying a round or spherical mold 11 having a cavity such as could be used to manufacture a basketball or volley ball. In FIG. 2, the spider 10 is adapted for carrying an oval mold 112 having a cavity such as could be used to manufacture a football. The upper half (11a or 12a) of each sectional mold is resiliently mounted on an upper grid member indicated at 14. The lower half (11b or 12b) of each mold is movably mounted on a lower grid member indicated at 15.

Referring to FIG. 1, an upper grid member 14 has a central hub area 16. Extending radially from the hub area is a plurality of regularly spaced spoke ribs 17. Each spoke rib terminates in an upper mold half mounting boss 18. Each mounting boss is laterally connected with adjacent bosses by a peripheral rib 19. At one side of the grid 14, two parallel hinge struts 20 extend outwardly from the rib 19.

As best shown in FIG. 3, a lower grid member 15 preferably matches an upper grid member 14 and also has a central hub area 21, a plurality of regularly spaced spoke ribs 22, a lower mold half mounting boss 23 at the end of each spoke rib and a connecting peripheral rib 24. The grid 15 also has two parallel hinge struts 25, but offset in relation to the upper hinge struts 20, extending outwardly from the rib 24.

The grid members 14 and 15 are preferably cast from a stainless steel alloy or a ductile iron composition so as to be light in weight yet resistant to centrifugal forces and the heat of the curing oven.

Referring to FIG. 3, each upper grid mold mounting boss 18 has an upper small diameter sleeve bore 28 opening down into a larger diameter spring bore 29. A preferably stainless steel spacer sleeve 30 is loosely fitted in bore 28 and extends a substantial distance downwardly into bore 29. A strong (e.g. 300-600 p.s.i.) compression spring 31, also preferably of stainless steel, is seated against a washer 32 in the upper end of bore 29. The under surface 33 of the boss is machined flat and is drilled to provide a blind bore 34. Referring briefly to FIG. 5, it will be observed that the mounting boss 18 of the spider adapted for carrying the oval molds 12 is similarly constructed.

The neck of each upper mold half 11a has a boss surface 35 which is substantially coextensive and in conformity with the under surface 33 of the mounting boss 18. At the center of the upper surface 35 is a mounting stud 36 having a tapped bore 37. On top of the stud 36 is placed a washer 38 for seating the lower end of the spacer sleeve 30. Around the stud 36 is another washer 39 for seating the lower end of the compression spring 31. Between the washer 39 and the edge of surface 35 is an aligning dowel 40 for insertion within the blind bore 34 in the under surface 33 of the mounting boss.

Each mold half 11a is attached to the mounting boss 18 by a cap screw having a hexhead 41 and a shank 42 threaded into bore 37. The length of sleeve 30 is such that when the screw shank 42 is securely threaded into bore 37, the cap screw can float or move a slight distance longitudinally within bore 28. The extent of down-v,

ward movement is limited by the screw head '41 a nd the extent of upward movement is limited, by the mold sprrecess. The compression spring'31 is' always tehdihg to move the screw head 41 into contact with the upp ejr su rface of the mounting boss 18 and the screw, shank 42, arid attached moldhalf 11a away the mounting boss.

"FIG. 3 shows the preferred normal position of the.

mold half 11a in relation to the mounting boss 18, when the spider 1%) is closed. Rotation of the mold half about the axis of the screw shank 42 is prevented by the blind dowel 40. The mold half 11a is maintained in mating alignment with the lower mold half 11 b by the strong compression spring 31. It has been found desirable that the spring 31 yield a pressure of approximately 20 pounds per lineal inch of periphery of the mating mold surfaces. A 's centrifugal. casting forces or heat from the curing oven are applied to the spider, any significant distortion of the grid member 14 will be compensated oregiialized resilient mounting of the upper mold half 1141.

Referring to FIG. 5, the neck of each'upper mold half;

12ais strengthened by longitudinal finsf44 and' has an up;

er surface 45. The center of surface has mammal recess 46 and a tapped bore 47. On top of the surface 45l.

isplaced an annular member 4 8,h'aving a hub 49 engaging the recess 46 and extending upwardly into the spring bore 29. Between the hub 49 and the edge of member 4 8 isgarra'ligning dowel 50 for insertion within'the blind bore 34in the under surface 33 of the mounting bossl Each. mold half12aisattached to the mounting bos s a manner similar to that described-above for a inoldj half 11a; that is, by a resiliently mounted cap screw having 'a head 41 and a shank 42 threade'd through hub; 49;

into bore 47.

Referring to FIG. 3, each lower grid mold mounting boss 23 has a lower small diameter s'leeve bore 52 opening upwardly into a larger diameter studbore '53. A mere;-

58 having adiameter slightly less 11m; thediameter of bore'53. The mounting stud also has a'tapped 1bore 59.

Between the stud 58 and 'the edge of'surface 57 an aligning dowel 60 for insertion within the blind bo're 5 6 on tl i e upper surface 55 of the mounting boss.

Each mold half 1112 is attached to the 'mountingboss 23 by a cap. screw having a heith'ead' 61 and a 'sh'ank 6i2 threaded into bore 59. *The'lerigthlof sleet/ 5415 such that when the screw shank-62 is securely threaded into bore 59, the lower end of stud 58 will be slightly above the lower end'of the bore 53 so that slight longitudinal and lateral movement of the mold half is. possible Provision for such a slight movement permits the accurate alignment of the mating upper mold halflliz during ates in'g 'of the spider, compensates oriequaliz es anyhistortion of the grid member 15; and r lessens the possibility jury to the mating mold surfaces during openingi Referring to FIG.- 5, each mounting boss 23 of the spider adapted for carrying theoval molds 12 also has a lower small diameter 'sleev'e bore 64 o-pei ing upwarjclly into a larger diameter bore 65. A sleeve 66, similar to sleeve 54, is loosely fitted in'b'ore 64 and extends a slight distance upwardly into bore65. The upper surface 67 of eachmounting boss is machined flat and is drilled to provide a blind bore 68. i

' The neck of each lower mold half 12!) is strengthened by longitudinal fins. 69 and has anunder surface 7 0'. The

center of surface 70 has an annular recess 71 and a tapped bore '72. An annular member 73 having a hub 74 en'- gaging recess 71 and extending downwardly into the bore 65 is located on the upper surface 67 of the mounting bore. Between the hub 74 the edge of member 73 is s12. ali n n QQWeL 7-5 tqnin sniqniwithint heibiindrbqre 68 of the'moimting boss-.

a h. mold: belt .212: s attache to. the mounting;- boss 23in. a manner similar -tothat; described above for amold half 11h; that i s, by a slightly-mpvablecap screwhaving a head 61 and as hank; 62; threaded throughhub 74 into bore 72.

A. 5 l .W l. Q,EIG; v hemsans s y s d b y n s s dmsmbe slr isns 151Q herinc ude rest r pin 3 hiil an t o s. r ied betwe n. he owe nds. f; a p of rectangular. traps- 81. xtendingownw rdly frorrr the uppsrsii imsmh t 14- Eas i st an lis pre e b tt shsdi o hefiris t an ide urfase a nge- W29 s y olts il; n imay e ow led or ccurate l nm nti sila eP 2 9 smevablst ithiav r ca y. elongate 191 84 nfl he ppst nds. ta. econd. nd Pr f ra ly ama a? mt tn t. fj staaeu r trap .85 xt nd n pw rdly r si he o a id ii m sr T5- Eachstran 5: P e erabl tochastic; e. ef hand de rface of a hinge st rut 2512s bybolts 86, and alsomayi bB. dQl|Vr d; s tsd- Q fill p n f. he p de B, ad ri sdindaafli s q h n f iasll sms dqup a dly nthe. elongate slots ,84 by a resilient means 7 such, as a; pair of coiled compression'springs 8 8, The lower portion; of. @91 s rin .8 s u q ssir tfixs Pos i n. hri e stud" 89-. Th sp'r n t d sea s prster lyi passd uidist nt @9 1 the -v i t ine. f. he s idtmsmhs 14. d 5. mm"

is dfi pw ridl r m a oss-P at 9 extending etw e e st n t shsdlhs f q a y 1t 1. he upper 1 11 9141 5. a h. spring rriesv a sp ngp u s ZZ Gh. s. sfs abl mi t hot r: hm f' p ins: t Et s t un rj l asa ns rss sq e 1m maintain the upper surface thereof in: abutting contact: with the undelisui' faceof the hinge rod 80.

Referring toLF IG. 3, the coupling means; for locking h s id. mem er 4 and 1 e e nsu t nt a y. par: el 1 s t is ads s snfihs n r l h b. a a 16- 1141 2i tl v i f s t a s. rid he oupl n a a nclud r 15 Xl i di a ii r elyz hr u h: i l. a 6 a d haying a; hl1e8t1195 a collar' -96-and an elongated body: 97 with a pair of;cross bores;9 at right angles to each other; Thefshaft body 97. isjournaled prefeirably in a' pair of upper and lower antifriction bearings 99;

When an upper grid;mem ber;14mis cast, the hub area 16 preferably has a transyerse; steel sleeve 100 inserted therein. The sleeve 100 is later machined to pro-vidga l ld i 9, qt hs bs ns 9the p'psnsu face 102 and the undersurface 103 of the hub, area .16 are also machined to provide annular grooves forinsertion of upper and lower bearing .seals'104 Eachbearw ing seal I 104 is of a grease and. heat resistant;- material suchas Teflon, suitablyencased for attachment as by, screws 105. Thebore .ofthe hub area 16. is lubricated by: a heat-resistant grease inserted through a conventional fitting 7106.

The'shaft body 97 .e rt ends downwardly into ahollow Cowling smlq i li r hwPpst-fi d f... 1. mb 08& preferably extends through the lower seal 104-and=seats against the lower bearing-99;; The sha ft body 97 fis; rigidy n ct do e. m mb r-19 s by o t l9 x endin through the cross-bores 98. The lower end-pf menrber 8 a ex e i r threads. 1 he hrea s flg e coars and quick-acting (e.g. standard Acme, 4'threads peninchl When the lower grid member 15 is cast,--the hub; area 21 preferably has a rough bore therethrough; The lower portion of the huhborejis thenma hi edtop q e.afinished bore 112 for receiving the drive spindle-1139f a;

casting.machine....not.shown)... Though the bore 112 is escapes shown as tapered, the hub area 21 could be adapted in any suitable manner for connection to a castingmachine.

The upper portion of the rough bore is machined to provide a finished bore 114. The upper surface of the hub area is also machined to provide a flat surface 115, a series of tapped bores 116, and if desired, dowel holes 117. The drive connection between the grid 15 and the machine spindle 113 is provided by an annular plate 118 seated on surface 115. The plate 118 has a flat upper surface 119, a hub 120 fitting in bore 114, and drive keys 121 for engagement with the drive spindle 113.

The coupling means further includes a hollow stud 122 seated on the upper surface 119 of the drive plate and secured thereto as by bolts 123 inserted in bores 116, and if desired, dowels 124 inserted through the drive plate into holes 117. The upper portion of the bore of the coupling stud has interior threads 125. The threads 125 should mesh quickly with the threads 110 of coupling member 108 and therefore are machined to provide a slight radial play (e.g. .010 inch). The lower portion of the coupling stud bore is preferably machined to receive an Allen-head bolt having a head 127 and shank 128 extending longitudinally of the coupling stud, through the drive plate hub 120, into a threaded bore 113a in the drive spindle of the casting machine.

When each grid member has been assembled with its respective mold halves as described above, a stay wire 129 is preferably inserted through the hexheads (41 or 61) of each mold half mounting screw.

5 at a slight angle (e.g. 5") from approximately the midpoint of the key. The key 132 is attached to the lug 130 by a pin or screw 137.

A latch lug 140 may also be cast at one side of the mating lip of an upper mold half 11a. :The latch lug is machined to provide a slot 141 having a vertical inner surface 142 (see FIG. 3) and an arcuate upper end 143. When the mold halves 11a and 11b are brought together by closing of the spider 10, the surface 142 will slide upon the key surface 136 and the slot end 143 will readily engage the pointed key end 134. Thus, the mold halves may be quickly and accurately aligned.

What is claimed is:

l. A spider for use with a rotational casting machine comprising, a wheel-like lower mold carrying member having a hub area adapted for connection to said machine, an upper wheel-like mold carrying member resiliently and yieldably hinged to said lower member, and means extending between the hub areas of said members for coupling the members together in substantially parallel planes.

2. A spider for use with a rotational casting machine comprising, a wheel-like lower mold carrying member having a hub area adapted for connection to said machine, an upper wheel-like mold carrying member resilwhen tha Spider 10 is Open the hinge Springs 88 are at iently and yieldably hinged to said lower member, a shaft maximum extension so that the hinge pin 80 is near thej top .of the elongate slots 84. The upper grid member may thus be readily lowered in position over the lower grid 15. When the grids are closed, the threads 110 on the coupling member 108 will be ready for engagement with threads 125 of the coupling stud 122. A suitable wrench (shown in dotted lines in FIG. 3) applied to the shaft head 95 will pull the upper grid 14 parallel to and in locked engagement with the lower grid 15. The resilient mounting of the upper mold halves (11a or 12a) and the movable mounting of the lower mold halves (11b or 12b) enables the mold halves to mate and align without injury to the mold surface during coupling of the grid members.

During the casting operation, the drive forces of the casting machine are applied to the lower grid 15 through the plate 118. Because the shank 97 of the upper grid coupling shaft is journaled in the bearings 99, the drive forces of the casting machine are applied to the upper grid 14 through the resiliently mated and aligned mold halves. Thus, the drive force is applied to the upper grid at several points and distortion thereof will be compensated or equalized.

After the casting operation, the shaft head 95 is turned to disengage the coupling member 108 from the coupling stud 122. As the threads 110 and 125 part, the upward movement of the grid 14 will be stabilized by extension of the hinge springs 88. During the opening movement, compression of the upper mold half mounting springs 29 is released so that when the coupling members are fully disengaged, the upper mold halves are lifted opening the molds without injury to the mating surfaces and freeing the molded articles from the mold cavities.

Referring to FIG. 6, when the spherical molds 11 have continuous pattern surfaces, that is, patterns or textures extending from one mold half to the other without interruption, it has been found desirable to provide means to accurately and quickly align the mold halves as the spider 10 is being closed. In most uses, the upper and lower dowels and 60 are sufliciently accurate. However, finely patterned molds benefit from a very accurate alignment.

Accordingly, a key lug 130 may be cast at one side of the mating flange of a lower mold half 11b. The key lug is machined to provide a seat for a registering pin or key 132. in cross-section, the lower end 133 of the aligning journaled transversely of the hub area of said upper member, and means extending between said hub areas and associated with said shaft for coupling the members together in substantially parallel planes.

3. A spider for use with a rotational casting machine comprising, opposed wheel-like mold carrying members resiliently and yieldably hinged together, oneof said members having a hub area adapted for connection to said machine, the other of said members having a shaft 49 journaled transversely of the hub area, and means extending between said hub areas and associated with said shaft for coupling the members together in substantially parallel planes.

4. A spider for use with a rotational casting machine comprising, a lower member, an upper member resiliently and yieldably hinged to said lower member, coupling means for locking said members together in substantially parallel planes, at least one mold section resiliently depending from said upper member and at least one mold section movably mounted on said lower member in alignment with a mold section on said upper member and defining a mold cavity when mated therewith.

5. A spider for use with a rotational casting machine comprising, a wheel-like lower member having a hub area adapted for connection to said machine, an upper wheel-like member resiliently and yieldably hinged to said lower member, a shaft journaled transversely of the hub area of said upper member, means extending between said hub areas and associated with said shaft for coupling the members together in substantially parallel planes, at least one mold section resiliently depending from said upper member and at least one mold section movably mounted on said lower member in alignment with a mold section on said upper member and defining a mold cavity when mated therewith.

6. In combination with a spider for use with a rotational casting machine, said spider including an upper member for carrying at least one depending mold section, a lower member for carrying at least one mold section in alignment with a mold section on said upper member planes, means for resiliently mounting a mold section anemone onisaid' uppermemben comprising, a cap screw having a extendingmovabl'y'through said member and at tached to the mold section, spacer meansmaintaining said cap a predetermined distance from said mold section, and, compression means extending between said member and mold section'tendingto move" said capdnto' contact withsaidmember,

T. Incombination-withaspider for use Witharotationall casting machine, saidspider including an upper memfor carrying at-l'east one depending mold section; a lower member for carrying atleastone mold section in alignmentrwith' a: mold section onsaid uppermember and defining a mold; cavity" when mated therewith, hinge meansresiliently and yieldab'ly connecting said upper and lower members andcoupling means for locking said up-- per and lower members together in substantially parallel planes, means forresiliently mounting a mold section on said: upper member, said mold' sectionhaving a. neck portion, comprising, a' cap screw havin g a shank extend ing movably through saidlmember' and attached to said neckportion,spacermeans maintaining said cap a-predetermined distance above said neck portion, and a coiled spring 'surrounding;said' shank" and said neck' portion and tending to move said mold section away from said upper, member. 7 I

8, In combinationwith a spider fonusewith'arotationaljcastingmachinqsaid spider including a lower'mold halfjcarryingmember, anupper mold half'carrying mema ber,,and coupling means, extending axially between said:

members, hingemeansc'onnecting said members'compris ing, a1fiiistpairfofnstraps' extending downwardly from;

the, edge offs-aid"v upper member, asecond pair; of strapsextending upwardly from the edge, of' saidlower-member each, having an elongate slot in the upper, end thereof, a hingepin carried between theilower ends of said'first pair ofg'strap s' and" extending through said elongate slots; and compression means carriedby said. second pair, of straps tending to, move said hinge pin away' from saidlower" member.. v .7 v v 7 I 9; combinatic'airr,with a spiderv for use; with" a rota= tiouallcasting machine, saidspide'r including alowerrmold half Carrying member; an upper mold half carrying mem her; ,and, coupling 3 means, extending axially between said members, hingemeans connectingsaidfmembers =comprising 'fa, first pair, of'straps extending downwardly from theedgevofi said upper member, a second. pair'of straps extending upwardly from the edge of said lower'mernber' eachhaving an elongateslot in the upper end thereof, a hingeipincarriedjbetween the lower ends of said first-pair ofistraps andextending through said elongate slots,,a'plateextending between .,said ,secondpair of straps, and coiled springmeanspn said plate tending to move said hinge pin away from saidllower member.

10,111 cmbinati0n witha spider for use with a-rota tional casting machine, said spider including'a' lower mold halflcarrying member, an upper mold half carrying member, andcoupling means extending axially between said ,m'embers, hinge means connecting said members comprising a firstpair of straps extending downwardly fromithe edgeofsaid upper member, a second pairof straps, extending upwardly from'the edge of said lower membereachvhaving an elongate slot in' the upperend' hereof; a ,hingepin carried between the lower ends of said pair of'straps and extending through said elongate slots, at least oneupwardly directed'stud supported betweensaidsecond pair of straps, at least one plunger in abuttingcontact with said hinge-pin and coiled spring means extending jbetween a stud and'plunger tending to movelhe hinge ,pin away from said lower member;

, 11.;v Incombination withia spider for use with arota tional casting machine, said spider including a wheel likes lower mold carrying grid liswingfzvhub area adapted to ba driven by said machine and" a wheel like upper mold carrying grid resiliently and yiefdably hinged' tosaid-L lower member; coupling means for-said grids-"comprising; a shaft 'journaled transversely of the hub arealof said up-- per-grid and having exterior threads on thelower endi thereof and a hollow stud-attachedto the-hub area: of said lower grid and havingginterior threads in" the upper end thereof meshing with said exterior threads, said shaft being rotatably engaged with said stud tolock saidtogether in substantially parallel planes; V

12. In. combination'with a: spider for use with a-rota-' tional casting machine, said spider including a wheel like lower mold-carrying grid havinga hub. area adaptedto be driven by'said machine and. a wheel like upper mold carrying grid, resiliently," and yieldably hinged to: said lower. member and having; a' hub area with a transverse bore, coupling means. for sa'idfgri'ds comprising, a shaft" journaled in bearings seatediin said here, a member hav ingexterior threads attached to" the'lowe'r end" of's aidlisha'ft and a. hollow stud attachedto the hubarea ofsaid lower. grid and havinginterior threads in the upper end thereof," meshing with saidexterior threads,,said' shaft being rota't able to mesh said threads lockingsaidlgrids together, in substantially parallel planes.

-l3.,In.combinationiwith a spider for. use with airo ta tional casting machine, said spiderv including oppos'edlup' per and lowermembers eachcarrying at least one mating mold half, means for registering said. mold halves. com-.

, prising, aregistering key havinga'pointedlupper enduandl a downwardly tapered, inner facing surface, said key,

being located, on .the periphery of, a lowenrnemb'enrnolii half, and a registering latch. having, an. arcuate' slot for: engaging said pointedendsandia vertical-surface for en-i gaging saidtapered surface," said latch being locatecL' on the. periphery of an upper. member. mold half;

14. In combinationwithsa spider for use witha-trotaa tional casting machine; said spider includingopposed up, fiei'xandlowerrmembersz each .carrying, at least .oneahemi spherical; moldv half, means for; registering said mold ,hal ves. to" define amold v cavity comprising, a registering, key having a pointed upper end and a downwardly tapered inner facing surface, said-key being located; on the periphery of a-lower memberfmold half, and a-regis-- tering; latch having an" arcuate slot for engaging, said pointed. end and a vertical surface for engaging; said tapered surface, said-latch being located on the periphery? of an. upper member mold half;

References Cited in the file of 'this'patent UNITED STATES PATENTS 258358 Locke- May-'30;-1882- 723,998- Fagan Mar: 31, 1903* 841,962 Hardy Jan. 22, 1907 1,575,688 Joannides Mar. 9, 1926? 1,773,810 Fairchild" Aug. 26, 1930 1,890,968 Carter Dec. 13, 1932 1,921,925 Johnson Aug. 8} 1933' 2,'262,l43 Kelm Nov. 11,1941 2,298,057 Kelm Oct. 6,1942 2,443,826 Johnson" June22; 1948 2,448,640 Weston- Sept. 7, 1948 2;469,892 Rfempel May'lO, 1949 2,624,072" Delacosteet 'al. J an; 6,1953" 2,745,138" Beattie; May 15; 1956' OTHER: REFERENCES Zweig: Rotational. Molding of Plastisolsf" from:- Modern Plastics, September1955. 

